1. Field of the Invention
The present invention relates to a transmission system, a receiver circuit for use in the transmission system, and a semiconductor memory device to which the signal transmission system is applied, and more particularly to a transmission system using a PRD (partial-response detection) method, a receiver circuit for use in the signal transmission system, and a semiconductor memory device to which the signal transmission system is applied.
2. Description of the Related Art
In recent years, with advances in semiconductor technology, the speed of processors (MPUs: Micro Processor Units) has increased dramatically. The performance of semiconductor memory devices, exemplified by DRAMS (Dynamic Random Access Memories), has also improved to some extent in terms of speed, but compared with the increase in processor speed, the disparity has been growing steadily.
Stated another way, processor performance has increased dramatically in terms of speed, whereas DRAM performance improvements have been dramatic primarily in terms of storage capacity. However, DRAM speed improvements have not been so dramatic as the increase in storage capacity, as a result of which the gap between the speed of DRAMs and that of processors has widened and this speed gap has become a bottleneck in boosting system (computer) performance in recent years. Furthermore, as chip sizes increase, the speed of signal transfers between devices and between constituent circuits within one LSI chip (semiconductor memory) is becoming a major limiting factor in chip performance.
If this situation continues, a situation may arise where the overall system speed cannot increase at all despite increased processor speed, eventually leading to stagnation of the information industry. There is therefore a growing need to increase the speed of semiconductor memory devices and, particularly, the data transfer speed in semiconductor memory devices.
The prior art and problems associated with the prior art will be described in detail later with reference to drawings.